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News: USA showered by a watery comet ~11,000 years ago, ending the Golden Age of man in America
http://dsc.discovery.com/news/briefs/20050926/mammoth_02.html
 
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Did a comet swarm strike America 13,000 years ago?

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Warhammer
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« on: August 31, 2010, 07:23:08 am »


Did a comet swarm strike America 13,000 years ago?
16:16 2 April 2010
Environment
Life
Space

Jeff Hecht, contributor

Add a new suspect to the list of what might have killed the ice-age megafauna of North America – a barrage of debris from a disintegrating comet. Instead of a four-kilometre comet blowing a single crater in the North American ice sheet 13,000 years ago, the infalling debris would have filled the sky with a series of megatonne-scale explosions like the Tunguska event of 1908.

A series of fiery blasts could be every bit as deadly as one big impact. That's why planetary scientists have warned that blowing up an asteroid about to hit the Earth could still cause major damage. But others hold that no cosmic catastrophe is needed to explain the demise of mammoths and mastodons, and the end of Clovis culture.

The new proposal comes from Bill Napier, an astronomer at Cardiff University, who in 1982 co-authored a book titled The Cosmic Serpent. In it, he and Victor Clube suggest that the outer planets sometimes divert giant comets into the inner solar system, where they fragment over thousands of years. The theory of coherent catastrophism claims that we live at a time of increased impacts, because one of those giant comets entered the inner solar system 20,000 to 30,000 years ago, leaving behind the Taurid meteor shower, Comet Encke and other debris.

In a paper now at Arxiv.org that is to appear in the Monthly Notices of the Royal Astronomical Society, Napier argues the real catastrophe was the Earth hitting a clump of debris from a 50- to 100-kilometre comet. "Running into thousands of fragments from this comet is a much more likely event than a single large collision," he says. "It gives a convincing match to the major geophysical features at this boundary," including the deposition of nanodiamonds contained in the fragments.

But recent studies continue to raise doubts about the impact theory. In December, researchers reported that they had found no geochemical signatures of an impact in the layer of sediment formed at the time.

Meanwhile, a different kind of catastrophe has been found 13,000 years ago - the sudden drainage of a huge Canadian lake. Meltwater at the base of the North American ice sheet had accumulated in the lake because it had nowhere else to go. Eventually whatever held the water in place along the edge of the glacier broke or melted, causing the water to flow away.

Geologists had looked in vain for evidence of drainage through the Saint Lawrence River into the Atlantic Ocean. Wallace Broeckner of the Lamont-Doherty Earth Observatory had suggested this would have caused a sudden dramatic cooling by shutting down the global conveyor belt of ocean circulation.

But a paper just out in Nature shows that instead the water drained north through the Mackenzie River, dumping some 9500 cubic kilometres of water into the Arctic Ocean. Broeckner says such an Arctic release might have been an even better climate trigger, obviating the need for an impact to cause the cold spell that occurred about 13,000 years ago.


http://www.newscientist.com/blogs/shortsharpscience/2010/04/did-a-comet-swarm-strike-ameri.html
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Warhammer
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« Reply #1 on: August 31, 2010, 07:25:54 am »


jlb on April 3, 2010 5:33 AM

http://www.unb.ca/passc/ImpactDatabase/ is the source of my point.
North America has many giant craters. Canada has Sudbury @ 250km and Manicougen @ 100km across. No explanation of extinction by impact makes sense in the face of so many violent and gigantic impacts. Vredefort in South Africa @ 300km makes the Chixulub impact in Yucatan @ 170km look small.

You have all heard pieces of a confusing and ever growing story of the large scale end of life on the Earth. Everybody seems to have an idea, and if global extinction was a flavor of ice cream, there is a new popular flavor every week.
Add to the mix the many other theories, now popular but unproven and you get a growing but clear picture. Some of these theories which include global glaciations: including instantaneous freezing of large animals in sub tropical climates. Polar wobbles including all the Milankovitch Theory ideas that pop up including the latest craze for 2012 and the Mayan cycle. Magnetic field variations with wobbles and shifts, polar flipping and orbital variations, sometimes mixed with plate shifting, mountain building and continental collisions all have there part and advocates.
Solar history and cycles is yet another subject. With the latest Voyager data showing a changing Heliosphere, it is only a matter of time until someone suggests that maybe the Earth went through a cosmic ray hotspot in our Galaxy. Why not?
Global volcanism whether you choose the Siberian traps, the Deccan traps, the North American plate or any other Mega volcano or volcanic blast needs to be included in the discussion and if something other than bacteria were left after the volcanic extinction event, I am fairly confident that these critters would be killed by a Gamma ray Burst in nearby space or a local Super Nova. LOL
It is getting funny or better yet, curiouser and curiouser!
All this stuff is going on with most if not all of the Earth covered by shallow seas.
The weird thing is that there is good evidence that most of these things happened very close to the same time. I mean by the time frame proposed by the advocates of these theories.
That does not include ongoing discussions in Cosmology. The Gravity-Mass people have all the big equipment and money, but the Electrical-Plasma people, seem to have the better theories. And if the growing discussion of changes in universal constants such as time and the possible changing speed of light, with time decreasing as we move forward, and Quanta shifting in red shift data all pointing to an ever changing and non constant universe around us, what are we to believe?

Catastrophe on a global scale happened with out a doubt!

Even if no discussion of religion is allowed to be included in the discussion, and it should be; we cannot be sure of what happened, when it happened or how it happened.
One thing is absolutely certain: the idea that this planet had billions and billions of years of time passing peacefully without any major disruptions is foolishness and what used to pass for common sense is still common but no longer makes any sense.
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Warhammer
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« Reply #2 on: August 31, 2010, 07:26:22 am »



July 20, 2009 | 10 comments
Did a Comet Cause a North American Die-Off around 13,000 Years Ago?
Tiny hexagonal diamonds suggest a massive impact during the late Pleistocene that could have wiped out the Clovis people, mastodons and other continental inhabitants--but the geologic evidence falls short for some skeptics

By Brendan Borrell   
 

COMET CLASH: James Kennett
and son Doug on Santa Rosa Island in California where they discovered more evidence that a comet caused an extinction event 13,000 years ago.
UC SANTA BARBARA
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0diggsdigg

Researchers have found shock-synthesized hexagonal diamonds on one of California's Channel Islands, which they say is the strongest evidence yet that a comet exploded in the atmosphere above North America, causing widespread extinctions there around 12,900 years ago. Skeptics, however, say the debate is far from over.

In 2007 researchers theorized that a comet set off continental fires that led to the mysterious disappearance of the Clovis people and the extermination of 35 mammal genera, including mammoths, mastodons, ground sloths and camels. The team documented a "black mat" of charcoal throughout North America that contains high levels of iridium, magnetic spheres, and nano-diamonds, which are consistent with such an airburst. The controversial theory also gibes with the 1908 Tunguska atmospheric detonation (also thought to be from a comet or meteorite) that leveled trees in Siberia, and it echoes the extraterrestrial impact widely believed to have wiped out the dinosaurs 65 million years ago.

Today, in Proceedings of the National Academy of Sciences, the same team reports on shock-synthesized hexagonal diamonds, known only from meteorite and other impact events, in a soot layer from Arlington Canyon on Santa Rosa Island in California. The canyon is famous for containing the earliest human remains in North America, dating back to 13,000 years, and the soot layer coincides with the disappearance of the pygmy mammoth from the island. In a documentary shown earlier this year on the Public Broadcasting Service's NOVA science show, the team also claimed that they discovered similar diamonds from the Greenland Ice Sheet dating to the same period.

But the evidence does not convince everyone. "I don't think much of this whole story," says geochemist Christian Koeberl of the University of Vienna in Austria, "Diamonds of any sort are not uniquely characteristic of impact events." He says that the major lines of evidence are still missing, including the presence of shocked minerals, including breccias and tektites as well as an impact crater. "At least three other groups searched for similar evidence in the same or similar samples and found none," he adds.

Briggs Buchanan, an archaeologist from Simon Fraser University in Burnaby, British Columbia, disputes the notion that humans declined following the purported impact. "We have shown that in California, specifically, that there [was] no severe decline in the resident population." He adds that other researchers have shown that the black mat varies in age across the continent and appears to have a variety of geologic origins.

What does the research team have to say about their doubters? "I'm so skeptical about the skeptics," says marine geologist James Kennett of the University of California, Santa Barbara. "We work in a different paradigm where different materials result from different kinds of impacts."
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Warhammer
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« Reply #3 on: August 31, 2010, 07:27:48 am »



July 20, 2009 | 10 comments
Did a Comet Cause a North American Die-Off around 13,000 Years Ago?
Tiny hexagonal diamonds suggest a massive impact during the late Pleistocene that could have wiped out the Clovis people, mastodons and other continental inhabitants--but the geologic evidence falls short for some skeptics

By Brendan Borrell   
 

COMET CLASH: James Kennett
and son Doug on Santa Rosa Island in California where they discovered more evidence that a comet caused an extinction event 13,000 years ago.
UC SANTA BARBARA
e-mail print comment
0diggsdigg

Researchers have found shock-synthesized hexagonal diamonds on one of California's Channel Islands, which they say is the strongest evidence yet that a comet exploded in the atmosphere above North America, causing widespread extinctions there around 12,900 years ago. Skeptics, however, say the debate is far from over.

In 2007 researchers theorized that a comet set off continental fires that led to the mysterious disappearance of the Clovis people and the extermination of 35 mammal genera, including mammoths, mastodons, ground sloths and camels. The team documented a "black mat" of charcoal throughout North America that contains high levels of iridium, magnetic spheres, and nano-diamonds, which are consistent with such an airburst. The controversial theory also gibes with the 1908 Tunguska atmospheric detonation (also thought to be from a comet or meteorite) that leveled trees in Siberia, and it echoes the extraterrestrial impact widely believed to have wiped out the dinosaurs 65 million years ago.

Today, in Proceedings of the National Academy of Sciences, the same team reports on shock-synthesized hexagonal diamonds, known only from meteorite and other impact events, in a soot layer from Arlington Canyon on Santa Rosa Island in California. The canyon is famous for containing the earliest human remains in North America, dating back to 13,000 years, and the soot layer coincides with the disappearance of the pygmy mammoth from the island. In a documentary shown earlier this year on the Public Broadcasting Service's NOVA science show, the team also claimed that they discovered similar diamonds from the Greenland Ice Sheet dating to the same period.

But the evidence does not convince everyone. "I don't think much of this whole story," says geochemist Christian Koeberl of the University of Vienna in Austria, "Diamonds of any sort are not uniquely characteristic of impact events." He says that the major lines of evidence are still missing, including the presence of shocked minerals, including breccias and tektites as well as an impact crater. "At least three other groups searched for similar evidence in the same or similar samples and found none," he adds.

Briggs Buchanan, an archaeologist from Simon Fraser University in Burnaby, British Columbia, disputes the notion that humans declined following the purported impact. "We have shown that in California, specifically, that there [was] no severe decline in the resident population." He adds that other researchers have shown that the black mat varies in age across the continent and appears to have a variety of geologic origins.

What does the research team have to say about their doubters? "I'm so skeptical about the skeptics," says marine geologist James Kennett of the University of California, Santa Barbara. "We work in a different paradigm where different materials result from different kinds of impacts."
http://www.scientificamerican.com/article.cfm?id=did-a-comet-cause-die-off
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Warhammer
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« Reply #4 on: August 31, 2010, 07:28:44 am »

rmforall at 02:25 AM on 07/23/09

widespread Carolina Bay type craters from Clovis comet 12,900 Ya BP? -- 0.7 M long NS crater with fractured red sandstone on SW rim, CR C 53A, 20 miles E of Las Vegas, NM: Rich Murray 2009.06.08
http://rmforall.blogspot.com/2009_06_01_archive.htm
Monday, June 8, 2009
http://groups.yahoo.com/group/AstroDeep/27
 
This post throughly presents mainstream research, worthy media accounts, and valuable links for open-minded exploration.
 
To illustrate, I herein quote the whole abstracts for the Richard B.  Firestone et al seminal report and a C. Vance Haynes, Jr. review.
 
As well as evidence for the probable time and cause of the extinction of  Clovis culture in the Americas, many sites are also in Europe.
 
The connection with Carolina Bays confirms a continental disaster, which may  have retarded the evolution of urban culture in the Americas, despite  generally favorable landscape, climate, water, and lack of large competing
mammals.
 
As a conscientious scientific amateur, I want to open up evidence and reason based dialogue re evidence I readily found for widespread fields of very similar craters in the Northern Hemisphere, starting with a specific,
convenient, accessible crater near Las Vegas, New Mexico.
 
Others can join in quickly locating similar fields in almost every state.
 
There is opportunity for amateurs to make very helpful contributions in exploring multiple research opportunities.
 
In mutual service,  Rich Murray, MA
 
Google Maps Satellite image link:
http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=Las+Vegas,+New+Mexico&
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Keith Ranville
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« Reply #5 on: August 31, 2010, 01:47:13 pm »



http://oakislandtreasurenewsarchives.blogspot.com/2010/07/saturn-earth-hexagon-box.html

Hexagon theory North America Via Saturn hexagon phenomena.

Keith,
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Adam Hawthorne
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« Reply #6 on: September 01, 2010, 07:14:27 am »

Impact hypothesis loses its sparkle
Shock-synthesized diamonds said to prove a catastrophic impact killed off North American megafauna can't be found
            
      

IMAGE: Tyrone Daulton is pictured with the transmission electron microscrope he used to search in vain for shock-synthesized nanodiamonds, evidence that a extraterrestrial object such as a meteorite killed off North...
Click here for more information.

      
            

About 12,900 years ago, a sudden cold snap interrupted the gradual warming that had followed the last Ice Age. The cold lasted for the 1,300-year interval known as the Younger Dryas (YD) before the climate began to warm again.

In North America, large animals known as megafauna, such as mammoths, mastodons, saber-tooth tigers and giant short-faced bears, became extinct. The Paleo-Indian culture known as the Clovis culture for distinctively shaped fluted stone spear points abruptly vanished, eventually replaced by more localized regional cultures.

What had happened?

One theory is that either a comet airburst or a meteor impact somewhere in North America set off massive environmental changes that killed animals and disrupted human communities.

In sedimentary deposits dating to the beginning of the YD, impact proponents have reported finding carbon spherules containing tiny nano-scale diamonds, which they thought to be created by shock metamorphism or chemical vapor deposition when the impactor struck.

The nanodiamonds included lonsdaleite, an unusal form of diamond that has a hexagonal lattice rather than the usual cubic crystal lattice. Lonsdaleite is particularly interesting because it has been found inside meteorites and at known impact sites.

In the August 30 issue of the Proceedings of the National Academy of Sciences, a team of scientists led by Tyrone Daulton, PhD, a research scientist in the physics department at Washington University in St. Louis, reported that they could find no diamonds in YD boundary layer material.

Daulton and his colleagues, including Nicholas Pinter, PhD, professor of geology at Southern Illinois University In Carbondale and Andrew C. Scott, PhD, professor of applied paleobotany of Royal Holloway University of London, show that the material reported as diamond is instead forms of carbon related to commonplace graphite, the material used for pencils.

"Of all the evidence reported for a YD impact event, the presence of hexagonal diamond in YD boundary sediments represented the strongest evidence suggesting shock processing," Daulton, who is also a member of WUSTL's Center for Materials Innovation, says.

However, a close examination of carbon spherules from the YD boundary using transmission electron microscopy by the Daulton team found no nanodiamonds. Instead, graphene- and graphene/graphane-oxide aggregates were found in all the specimens examined (including carbon spherules dated from before the YD to the present). Importantly, the researchers demonstrated that previous YD studies misidentified graphene/graphane-oxides as hexagonal diamond and likely misidentified graphene as cubic diamond.

The YD impact hypothesis was in trouble already before this latest finding. Many other lines of evidence — including: fullerenes, extraterrestrial forms of helium, purported spikes in radioactivity and iridium, and claims of unique spikes in magnetic meteorite particles — had already been discredited. According to Pinter, "nanodiamonds were the last man standing."

"We should always have a skeptical attitude to new theories and test them thoroughly," Scott says, "and if the evidence goes against them they should be abandoned."

###

http://www.eurekalert.org/pub_releases/2010-08/wuis-ihl082510.php
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